Thermoelectric (TE) devices convert heat directly to electrical power, or conversely, create cooling directly from electrical power. The devices are entirely solid state, with no moving parts to wear out. They are very rugged and can last indefinitely. Their two main shortcomings have been A) low efficiency, and B) operation at high temperatures. The low efficiency relegates TE devices to a few applications where their simplicity and ruggedness outweighs the inefficiency, such as sensors and waste heat energy converters. More recently, advances in semiconductor TE devices have made practical small coolers and temperature controllers that can both heat or cool as needed to control a temperature. Applications range from cooling computer chips, cooling seats in cars, recharging car batteries from engine wasted heated to appliances for the home.
The potential for TE devices, however, is much greater. If the efficiency can be increased and the reduce the operational temperatures near room temperature (300K), TE devices can begin to supplant mechanical compressor refrigeration systems, gasoline generators, geothermal power production and more. TE devices could play a significant role in the energy production, home heating/cooling and general energy management of the future.
More recent advances in TE devices have shown that quantum dot and superlattice structures combined with semiconductor technology can produce even higher efficiency factors. One such example is disclosed in U.S. Pat. No. 6,605,772 filed May 24, 2001 by Harman, wherein PbSeTe/PbTe quantum dot superlattice structure was said to be capable of a figure of merit (ZT) of 0.9 near room temperature (300K). Another example is shown in the U.S. Pat. No. 7,687,705 titled “Efficient Thermoelectric Device,” filed Apr. 9, 2007 by ILA. The above mentioned patent documents are hereby incorporated herein by reference.
Although improvements have been made, further improvement in lowering operational temperature and efficiency are needed before TE devices can compete with the energy conversion machines that presently dominate industry. To reach their full potential, these improvements will need to use techniques that can be manufactured economically and result in rugged and reliable devices.
Therefore there is a clear need for thermoelectric devices that have improved efficiency, are easy to manufacture, and are rugged and reliable devices in the field.